Khalifa Haftar's forces, backed by former Gaddafi brigades, said they had seized control of most areas in Sirte after brief clashes with Sirte Protection and Security Force units, which pulled out after being abandoned by Brigade 604 - a Madkhali force that was formed after the city was freed from ISIS in 2016.

For weeks, Haftar's forces have been launching sporadic attacks on Sirte with several air attacks by UAE drones, which caused several deaths from the Sirte Protection and Security Force.

Sirte Protection and Security Force sources said their force was betrayed by Brigade 604, whose personnel are mostly from Sirte and tasked with securing their city from the inside.

The sources added that most of the city is now under the control of Haftar's forces and former Gaddafi brigades, except for some neighborhoods in which few brigades are trying to repel the rest of the attack.

With an air cover, Haftar's forces advanced Monday on Sirte from eastern and southern frontlines before 604 Brigade gave them the green light to advance from inside the city, thus forcing Sirte Protection and Security Force brigades to retreat allowing Haftar's forces to enter the city without fighting.

Gaddafi's hometown Sirte is still with the Gaddafi regime of Libya and that made it give the city to ISIS without any resistance as most militants were previous Gaddafi brigades' personnel.

Madkhali-Salafist Brigade 604 is made mostly from Sirte locals. It didn't take part in the fighting against ISIS. The brigade was formed to secure the city and it angered Sirte Protection and Security Force at the time, citing distrust in the personnel for their Salafist ideology that is linked to Saudi Arabia, which is backing up Haftar.